berkay_91
Newbie level 6

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I want to use HV9910 LED driver IC, can you tell me which pins must be connectAny doubts what L.D. and P.D. means?
View attachment 198545
Which laser driver are you considering?
Datasheet parameters suggest that this laser diode (L.D.) can't be safely operated without using feedback of built in photo diode (P.D.) because maximal threshold current and output power at minimal threshold overlap, you can't guarantee to keep maximum optical output (avoid breaking the laser) by only limiting current.
ok, can ı use LM317? how to read feedback current from P.D. pin?Berkay,
You can not use a switched mode regulator for a laser.
It must be very fast to regulate current from PD current ratio thus using a linear circuit. The PD captures a small amount of the laser which has negative resistance properties starting up "lasing" so stability from loop gain and minimal delay is important to minimize this error in regulating voltage or limiting current.